What type of ducts are installed below ground level?

The term "Underground Ducts" accurately describes ducts specifically designed to be installed below ground level. These ducts are often utilized in commercial and industrial settings for transporting air, HVAC needs, or other utilities underground, allowing for a more efficient use of above-ground space while also providing necessary insulation and protection from external elements.

Underground ducts are engineered to withstand underground conditions, ensuring proper ventilation or airflow in various applications while managing thermal gradients. The other choices, while they might imply some form of underground placement, do not specifically denote a recognized category of ducts that comply with the same standards and specifications as underground ducts.

For example, "subterranean" and "buried" might refer to similar concepts, but "underground" is the standardized term used in industry literature and codes. "Concealed ducts" typically refer to ducts hidden from view but not necessarily installed underground, focusing instead on aesthetics and architectural design rather than positioning. This specificity is crucial when assessing installation code compliance and design requirements in mechanical systems.